Spray booth

ABSTRACT

A spray booth includes spray means mounted above a support and arranged for spraying work thereon with the production of attendant overspray. At least one enclosed overspray collecting chamber is located beside the support. The chamber has an air inlet port at its lower inner end and an air exhaust port at its upper end. An exhaust fan entrains the overspray and passes it through the chamber. A wash liquid spray cooperates with baffles and a contact screen in absorbing the overspray in the wash liquid. Combination shield and guide elements positioned on both sides of the support transversely of the chamber shield the booth and guide the flow of air into the chamber.

United States Patent Inventors James P. Petermmm 3,170,384 2/1965 Krantz et a1. 98/115 X Eugene; 3,424,129 1/1969 Peeps etal 118/326X Robert J- Slagle, Springfield; Russell W. 3,390,400 6/1968 Dock 98/115 SB Wilson, Eugene; Leslie M. Steffensen, 3,475,202 10/1969 Bok 1 18/326 X A I N 2mm all e FOREIGN PATENTS pp o. Filed Nov. 171967 222,861 7/1959 Australia 98/115 Patented Aug. 24, 1971 Primary Examiner-John P. Mclntosh Assignee Georgia-Pacific Corporation Attorney-Eugene D. Farley P0rt1and,0reg.

ABSTRACT: A spray booth includes spray means mounted SPRAY BOOTH above a support and arranged for spraying work thereon with 4 Claims" Drawing m the production of attendant overspray. At least one enclosed overspray collecting chamber 13 located beside the support. US. Cl 118/326 The chamber has an inlet port at its lower inner end and an Bosc 11/ air exhaust port at its upper end. An exhaust fan entrains the Field ofseflrch .t 118/326, overspray and passes it through the Chamber A wash i i DIG 798/115 SB spray cooperates with baffles and a contact screen in absorbing the overspray in the wash liquid. Combination shield and Reiemm CM guide elements positioned on both sides of the support trans- UNITED STATES PATENTS versely of the chamber shield the booth and guide the flow of 2,230,646 2/1941 Klausmeyer 1 18/D1G. 7 air into the chamber.

Patented Aug. 24, 1971 James RPe'l'ermcmn Roberl' J. Slagle Russell W. Wilson Leslie Mfiieffensen I N VE'N TOR SPRAY BOOTH This invention relates to a spray booth for applying sprayed material to articles arranged on a support. It pertains particularly to a spray booth for use in spraying plywood adhesives on wood veneers traveling rapidly on a moving support past a spray station. The invention is described herein with particular reference to such a use, although no limitation thereby is intended.

In one method of plywood manufacture, wood veneers supported on a rapidly moving conveyor are moved past a spray station which applies to their upper surfaces a uniform pattern of a suitable adhesive. In this procedure, the adhesive may be used in the form of a viscous liquid, or as moist particles. In either case, there is produced an overspray which escapes as a fine suspension into the atrnospheresurrounding the spray installation. Since plywood adhesives at best are severely irritating, and at worst highly toxic, it is important to provide the spray station with facilities for intercepting and collecting the overspray before it poisons the operating personnel and soils the operating environment.

It accordingly is the general purpose of the present invention to provide a spray booth which is applicable to the large scale application of sprayed materials onto articles passing a spray station on a rapidly moving conveyor, which collects the overspray efficiently and removes it from the operating environment, which shields the work and the environment effectively while at the same time permitting ready inspection of and access to the work; and which, most importantly, performs the indicated functions without creating an air turbulence which would destroy a critical pattern of the materials applied to the work.

Generally stated, the spray booth of our invention includes suitable spray means mounted upon a support on which the articles to be sprayed are arranged. At least one enclosed chamber is positioned beside the spray means for collecting the overspray developed by the spraying operation.

The chamber is elongated vertically and has an air inlet port at its lower end opposite the support. An air exhaust port is located at the upper end of the chamber. An exhaust fan associated with the chamber maintains an airstream flowing upwardly therethrough, thereby entraining the overspray and passing it through the chamber.

Wash liquid spray means are mounted in the upper part of the chamber. This directs a spray of suitable wash liquid downwardly against baffle means arranged in the chamber for dispersing the wash liquid spray and increasing its contact with the overspray. Collecting means located in the lower portion of the chamber collect the wash liquid and its burden of overspray.

As additional features, a contact screen may be positioned in the chamber between the air inlet port and the baffle means for increasing the contact of the wash liquid with the air-entrained overspray. Also, combination shield and air guide means may be positioned on opposite sides of the sprays for shielding the unit further and for guiding the flow of air into the air inlet port of the chamber.

The manner in which the foregoing and other objects of this invention are accomplished will be apparent from the accompanying specification and claims considered together with the drawings wherein:

FIGS. 1 and 2 are views in end and side elevation, respectively, partly broken away to show interior construction, of the spray booth of our invention;

FIG. 3 is a detail view of a contact screen employed in the spray booth; and

FIG. 4 is a perspective view of combination overspray shield and guide means employed in the spray booth.

Considering the foregoing in greater detail and with particular reference to the drawings:

Where the spray booth of our invention is to be used in spraying material on the upper surfaces of rapidly moving planar articles, as in spraying plywood adhesives on the upper surfaces of wood veneers, the work support and work spray arrangement illustrated in FIGS. 1 and 2 is employed.

In this arrangement, a conveyor 10 having associated worksupport members 12, moving on rails 14, supports wood veneers 16.

The conveyor drives the veneers past a spray station containing a spray head assembly housed in a booth designed to shield the spraying operation and collect the overspray resulting therefrom. As indicated above, the overspray comprises a mist or fine dispersion of sprayed material which does not adhere to the work, but is dispersed into the atmosphere. If not collected, it may cause severe discomfort and hazard to the operating personnel, as well as unpleasant and dangerous soil ing of the premises surrounding the spray station.

The spray head assembly used in the spray booth may be variously comprised to suit particular spray applications. In a typical instance it may comprise a pipe 20 communicating with branch conduits 22 each of which communicates with and supports a suitably designed work spray head 24. The spray heads are arranged and constructed in a manner calculated to apply a predetermined pattern of sprayed material on the exposed upper surface of the work.

A collection pan 26 is placed below the work for the collection of nonair-entrained sprayed material which escapes the work. The residual air-entrained overspray is collected in the herein described spray booth, the general construction of which also is shown in FIGS. 1 and 2.

The spray booth includes at least one, preferably a pair, of enclosed overspray collecting chambers indicated generally at 30. These are located opposite each other, and are arranged longitudinally of the spray station.

Each overspray collecting chamber 30 comprises a housing 32 which is elongated vertically sufficiently to extend substantially above the spray assembly. The housing is provided with an air inlet port 34 which lies opposite the work and the spray heads. The bottom of the chamber is formed with a collecting pan 36 which collects the wash liquid and conveys it to waste.

In the illustrated and preferred form of the invention, the upper ends of a cooperating pair of overspray collecting chambers located on opposite sides of the work are open and communicate with a bifurcated extension 38 which joins the two chambers and integrates them into a single, hood-shaped unit. Extension 38 has at its upper end an exhaust port 40 which communicates with an exhaust conduit 42 leading to the exterior. An exhaust fan assembly, indicated generally at 44, is mounted on the exhaust conduit. It establishes and maintains a flow of air through intake ports 34, upwardly through overspray collecting chamber 30 and associated extension 38, through exhaust port 40, and outwardly through exhaust conduit 42.

The airstream thus established entrains emanating from the spray heads. The overspray is drawn upwardly through the collecting chambers where it meets a counter current stream of a suitable wash liquid. This is introduced into the top of the chambers through conduits 46 feeding wash liquid spray heads 48. These are arranged to spray a fine spray of water or other suitable wash liquid downwardly through the chambers.

Suitable baffle means are interposed between wash liquid spray heads 48 and inlet port 34 to assist in securing efficient contact of the wash liquid with the air-entrained overspray.

Although the baffles may be variously contoured and arranged, a suitable system is illustrated in FIG. 1. As shown in that figure, a plurality of baffles 50, 52, 54, 56, 60, 62, 64 and 66 surround wash liquid spray heads 48 so that the wash liquid discharged therefrom impinges upon the baffles and is directed toward all portions of the chamber.

Further to assist in securing intimate contact between the wash liquid and the air-entrained overspray, there may be provided in each chamber a contact screen 70. This may be variously constituted, but in general comprises a frame 72 enclosing and supporting a screen 74 which may comprise, for example, an aluminum screen having a mesh size of about onethe overspray eighth inch, FIG. 3. A closure flange 75 is fixed across one end of the screen.

- Screen mounting means are provided for positioning the screen removably in a location at which it must be traversed by the airstream and in which it also intercepts the flow of wash liquid. As shown also in FIG. 1, the mounting means comprise upper and lower. support brackets 76, 77 and end guide slot 78. These are positioned so that the screen lies diagonally across the chamber, opposite inlet port 34, and below. wash liquid spray heads 48, with closure flange 75 of the screen overlying grid slot 78.

Thus all of the material entrained in the airstream must pass 7 through the screen. At the same time, the wash liquid beating upon the screen contacts the overspray and effectively dissolves or suspends it. in addition, the force of impact of the wash liquid spray on the upper surface of the screen dislodges any particles which may collect upon it and keeps the screen clean.

Also provided are combination shield and guide means for preventing the escape of overspray to the exterior of the booth, while at the same time guiding the airstream which entrains the overspray into inlet ports 34 of the overspray collecting chamber. The construction of the combination shield and guide means is shown particularly in FIG. 4 and its manner of mounting in FIGS. 1 and 2.

Preferably there are two of the shield and guide assemblies located transversely of the support, upstream and downstream of the spray assemblies respectively.

In its preferred form, each combination shield and guide unit comprises a pair of plates 82, 84. The plates are joined at their upper ends and are spaced apart at their lower ends by means of braces 86, 88 and centrally located partition plate 90. The shield and guide unit thus is open at its bottom and open at its ends.

- As seen particularly in FIG. 1, its open ends are closely adjacent inlet ports 34 of collecting chambers 30. Accordingly an ail-stream is established through the open bottom of the shield and guide member, out through the sides thereof, and into-the collecting chambers in the manner illustrated by the arrows of FIG. 4.

To afford ready access to the work on supports 12, combination shield and guide units 80 preferably are suspended pivotally by their upper ends. For this purpose they are provided with bearings 92 extending upwardly from both sides. The bearings journal pivot pins 94 supported on the inner walls of collecting chambers 30. Accordingly the shield and guide units normally are suspended vertically in opposed positions. However, when the operator wishes to inspect the work more closely, or rearrange it, the shield and guide units may be swung outwardly about pivot pins 94.

OPERATION opposite open ends thereof into inlet ports 34 of the collection chambers. Thence it passes upwardly through the collection chambers, through chamber extension 38, and out through the exhaust conduit 42.

The overspray from the spray units, i.e. the material not deposited on the work but dispersed as a fine mist or air suspension, is entrained in this airstream. it enters the lower part of collecting chambers 30 through inlet ports 34 and passes upwardly countercurrent to a spray of wash liquid introduced through spray heads 48. During its travel, it is scrubbed by the spray, assisted by contact with baffles 52-64 inclusive.

Further assistance is given by screen 70 which insures uniform contact of the overspray material with the scrubbing liquid. At the same time, the screen is kept clean by impingement of the wash liquid spray on its upper surface.

The scrub liquid with its burden of collected overspray is collected in collecting pan 36 and recycled, or passed to waste.

There thus is provided an efficient unit for spraying articles such as plywood veneers on a large commercial scale at a high production rate. The spraying operation is attended by a minimum escape of overspray to the outside and hence with minimum hazard to operating personnel and minimum soiling of the environment surrounding the spray booth. These advantages are gained, furthermore, without disturbing carefully established and critical spray patterns, and without screening off the spray area from convenient inspection and access.

It is to be understood that the form of our invention herein shown and described is to be taken as an illustrative example of the same and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of our invention.

Having thus described our invention, we claim:

1. A spray booth for applying sprayed material to articles arranged on a support, the spray booth comprising:

a. work spray means mounted above the support and arranged for spraying the articles thereon with the production of attendant overspray,

b. at least one enclosed overspray collecting chamber positioned beside the support, longitudinally thereof,

c. the chamber being elongated vertically and having an air inlet port at its lower inner end opposite the support and an air exhaust port at its upper end,

d. exhaust fan means operatively mounted in the chamber for maintaining an airstream upwardly therethrough, thereby entrainirig the overspray and passing it through the chamber,

e. combination overspray shield and air guide means positioned on both sides of the work spray means, transversely of the support, opposite the air inlet port of the chamber for guiding the flow of air into the same,

f. wash liquid spray means in the upper part of the chamber for spraying wash liquid downwardly therethrough, countercurrent to the airstream,

g. baffle means mounted in the chamber opposite the wash liquid spray means for dispersing the wash liquid spray and increasing its contact with the overspray, and

h. wash liquid collecting means at the bottom of the chamber.

2. The spray booth of claim 1 including pivotal mounting means pivotally supporting the upper end of the combination shield and guide means.

3. The spray booth of claim 1 wherein the combination shield and guide means comprises conduit means open at its bottom for intake of air-entrained overspray and on its end up posite the air inlet port for discharge of air-entrained overspray. I

4. The spray booth of claim 3 wherein the conduit means is of substantially triangular transverse cross section and formed from a pair of plates interconnected by interposed braces, the plates being joined at their upper ends and spaced at their bottom ends. 

1. A spray booth for applying sprayed material to articles arranged on a support, the spray booth comprising: a. work spray means mounted above the support and arranged for spraying the articles thereon with the production of attendant overspray, b. at least one enclosed overspray collecting chamber positioned beside the support, longitudinally thereof, c. the chamber being elongated vertically and having an air inlet port at its lower inner end opposite the support and an air exhaust port at its upper end, d. exhaust fan means operatively mounted in the chamber for maintaining an airstream upwardly therethrough, thereby entraining the overspray and passing it through the chamber, e. combination overspray shield and air guide means positioned on both sides of the work spray means, transversely of the support, opposite the air inlet port of the chamber for guiding the flow of air into the same, f. wash liquid spray means in the upper part of the chamber for spraying wash liquid downwardly therethrough, countercurrent to the airstream, g. baffle means mounted in the chamber opposite the wash liquid spray means for dispersing the wash liquid spray and increasing its contact with the overspray, and h. wash liquid collecting means at the bottom of the chamber.
 2. The spray boOth of claim 1 including pivotal mounting means pivotally supporting the upper end of the combination shield and guide means.
 3. The spray booth of claim 1 wherein the combination shield and guide means comprises conduit means open at its bottom for intake of air-entrained overspray and on its end opposite the air inlet port for discharge of air-entrained overspray.
 4. The spray booth of claim 3 wherein the conduit means is of substantially triangular transverse cross section and formed from a pair of plates interconnected by interposed braces, the plates being joined at their upper ends and spaced at their bottom ends. 